The CEC 2017 conference has just concluded. In contrast with CEC 2014 and its antecedents, which attracted no press, it looks as though the taboo surrounding climate geoengineering has finally been broken. Climate-change doomsayers are about to discover that they cannot have it both ways. They cannot claim that humanity faces an imminent "civilization-ending" crisis, and then deny anxious citizens the right to debate measures that might forestall it—measures that carry risk, obviously, but which experts agree are relatively fast-acting, inexpensive and easy to reverse. The "moral-hazard" genie—the fear that we won't decarbonize if we believe there is a quick climate fix—is out of the bottle.